Does Wuuthrad Work on Orcs?

Wuuthrad's bonus against elves does not apply to Orcs (considered elves in some lore) or Orc vampires. This issue has been addressed by version 1.3. 2 of the Unofficial Skyrim Patch; it sets up the artifact to affect both.

Do orcs count as elves in Skyrim?

Orcs Are Actually Elves in The Elder Scrolls 5: Skyrim.

Does Wuuthrad work on Falmer?

The weapon bears the inherent ability of dealing 1.2x damage to Altmer, Bosmer, Dunmer, and Falmer. The effect is not considered an enchantment, so Wuuthrad is affected by the Elemental Fury shout.